Prostate cancer is the most frequently diagnosed solid tumor and the second leading cause of cancer death among American men. Although there is considerable mortality associated with this disease, many prostate cancer patients live for decades after their diagnosis. There is a significant burden of disease on survivors, as this cancer has a considerable impact on quality of life. In particular, various treatments for prostate cancer uniquely affect survivors overall health and daily existence. Unfortunately, there are few data examining the long-term effects of prostate cancer and its treatment on survivors' quality of life. This pressing need for more data led the NCI's Prostate Cancer Progress Review Group to recognize the study of quality of life as a research priority. We propose a population-based, longitudinal cohort study that will examine long-term (10-13 years post diagnosis) health-related quality of life (HRQOL) outcomes in middle-aged men (under age 65) diagnosed with prostate cancer in King County, Washington. This study will address the following specific aims: 1) To assess long-term HRQOL outcomes following treatment for prostate cancer in this population-based cohort, 2) To specifically examine the use of erectile aids in men with prostate cancer and to assess the effect of sexual dysfunction and its treatment on HRQOL in these patients. As a secondary aim, we will reassess and compare the psychometric properties of two of the most commonly used HRQOL instruments for prostate cancer patients. In addition to confirming the reliability and validity of these questionnaires in our cohort, this psychometric analysis will prove helpful to other investigators who wish to use these instruments to study long-term HRQOL outcomes in their populations. The proposed study takes advantage of an existing, unique source of data collected on 753 patients diagnosed between 1993-1996 and followed for 10-13 years (through 2006). Baseline data collection, including HRQOL, is already completed. Follow-up patient surveys, physician surveys, medical record reviews, and linkage with the Seattle-Puget Sound Surveillance, Epidemiology and End Results (SEER) registry, will be used to generate long-term HRQOL information and to identify patients with evidence of clinical progression/recurrence or death. Appropriate multivariable linear regression models will be used to achieve the aims described above. Results from this study will provide a better understanding of how prostate cancer and its treatment alter quality of life. This, in turn, will aid in clinical decision making and assist in designing interventions to improve outcomes in prostate cancer survivors.